1. Field of the Invention
The present invention generally relates to the production of commercial and medical radioisotopes and more particularly to a method and apparatus for producing such radioisotopes during normal operation of a commercial nuclear power reactor.
2. Description of the Prior Art
It is generally known that radioisotopes may be produced in a nuclear reactor by using some dedicated target tubes located therein.
By way of example, prior art patents teach various schemes for producing and using the radioisotopes produced in the nuclear reactor.
U.S. Pat. No. 4,393,510 teaches that a nuclear reactor may have flux enhanced Thorium fuel elements blanketed around the active region of a rector core and between the core barrel and the thermal shield to produce radioisotopes such as Uranium 233 (U-233) therein. These fuel elements are disposed within the reactor to be removed and reinserted during refueling or reactor outage. However, there is no teaching of how to use target tubes and encapsulated target material optimally loaded within the reactor to maximize the production of Plutonium 238 (Pu-238) rather than U-233.
U.S. Pat. No. 4,196,047 teaches the use of specimen holders with encapsulated target material for monitoring nuclear reactors. Again, there is no teaching of such target material being optimally loaded in the reactor to maximize Pu-238 production.
U.S. Pat. No. 4,475,948 teaches the use of Lithium Aluminate to produce Tritium by neutron flux in a nuclear reactor but again fails to teach any optimized method for producing Pu-238.
The present invention is drawn to a method and apparatus for optimizing the production of Pu-238 in a nuclear reactor. To accomplish this end, the production of Pu-238 is confined to replaced target cells located in the inside of the active volume of the reactor core where it can maximize the neutron flux for target irradiation. The invention modifies some existing nuclear fuel assembly by removing some fuel rods and replacing them with target rods and/or water filled rods to produce the desired target cells. The combination of fuel, target and water rods is unique in that selective combinations and locations of these rods within the target cell assembly tailors the neutron energy spectrum for the purpose of optimizing the Pu-238 production while minimizing the production of other, unwanted irradiation by-products.
In view of the foregoing it will be seen that one aspect of the present invention is to provide a method and apparatus for optimized Pu-238 production in a nuclear reactor.
Another aspect is to provide the production of Pu-238 radioisotope during normal reactor operation periods.
Still another aspect is to provide an optimized radioisotope production system of replacement isotope target rods for selective fuel rods.
Still yet another aspect is to provide an optimized radioisotope production system of selectively replaced fuel rods with target rods and water filled rods.
These and other aspects of the present invention will be more fully understood after a perusal of the following description of the preferred embodiment when read in conjunction with the following drawings.